Serum vitamin C and the prevalence of vitamin C deficiency in the United States: 2003-2004 National Health and Nutrition Examination Survey (NHANES).
Level 4 - case-series / case-control
Cross-sectional population survey (NHANES 2003-2004)
PubMed 19675106 · doi:10.3945/ajcn.2008.27016
What was done
Total serum vitamin C concentrations were measured in a nationally representative cross-sectional sample of 7,277 noninstitutionalized US civilians aged 6 years or older during NHANES 2003-2004. Deficiency was defined as serum concentrations below 11.4 micromol/L, and findings were compared with historical data from NHANES III (1988-1994).
What was found
The age-adjusted square-root transformed mean serum concentration was 51.4 micromol/L (95% CI: 48.4, 54.6). The overall age-adjusted prevalence of vitamin C deficiency was 7.1 +/- 0.9%, compared with approximately 13% in NHANES III. Women had higher concentrations than men across race-ethnic groups (P < 0.05). Adult smokers had approximately one-third lower mean concentrations than nonsmokers (35.2 vs 50.7 micromol/L in men; 38.6 vs 58.0 micromol/L in women). Mean vitamin C concentrations increased (P < 0.05) and deficiency prevalence decreased (P < 0.01) with increasing socioeconomic status. Recent supplement use or adequate dietary intake was associated with reduced deficiency risk (P < 0.05).
Why it matters
This study provides updated national benchmark data showing improved vitamin C status across the US population over a decade, while identifying smokers and lower-income populations as remaining vulnerable to deficiency.
Limits
The cross-sectional design cannot determine causality. Institutionalized populations and children under 6 years were excluded. The abstract does not provide exact odds ratios, adjustments for potential dietary confounding variables, or long-term clinical outcome measures.
Cited by
- supports Very few children are deficient in vitamin C.